Effectiveness of polypill for primary and secondary prevention of cardiovascular diseases (PolyIran): a pragmatic, cluster-randomised trial

Abstract

Background A fixed-dose combination therapy (polypill strategy) has been proposed as an approach to reduce the burden of cardiovascular disease, especially in low-income and middle-income countries (LMICs). The PolyIran study aimed to assess the effectiveness and safety of a four-component polypill including aspirin, atorvastatin, hydrochlorothiazide, and either enalapril or valsartan for primary and secondary prevention of cardiovascular disease. Methods The PolyIran study was a two-group, pragmatic, cluster-randomised trial nested within the Golestan Cohort Study (GCS), a cohort study with 50 045 participants aged 40-75 years from the Golestan province in Iran. Clusters (villages) were randomly allocated (1:1) to either a package of non-pharmacological preventive interventions alone (minimal care group) or together with a once-daily polypill tablet (polypill group). Randomisation was stratified by three districts (Gonbad, Aq-Qala, and Kalaleh), with the village as the unit of randomisation. We used a balanced randomisation algorithm, considering block sizes of 20 and balancing for cluster size or natural log of the cluster size (depending on the skewness within strata). Randomisation was done at a fixed point in time (Jan 18, 2011) by statisticians at the University of Birmingham (Birmingham, UK), independent of the local study team. The non-pharmacological preventive interventions (including educational training about healthy lifestyle-eg, healthy diet with low salt, sugar, and fat content, exercise, weight control, and abstinence from smoking and opium) were delivered by the PolyIran field visit team at months 3 and 6, and then every 6 months thereafter. Two formulations of polypill tablet were used in this study. Participants were first prescribed polypill one (hydrochlorothiazide 12.5 mg, aspirin 81 mg, atorvastatin 20 mg, and enalapril 5 mg). Participants who developed cough during follow-up were switched by a trained study physician to polypill two, which included valsartan 40 mg instead of enalapril 5 mg. Participants were followed up for 60 months. The primary outcome-occurrence of major cardiovascular events (including hospitalisation for acute coronary syndrome, fatal myocardial infarction, sudden death, heart failure, coronary artery revascularisation procedures, and non-fatal and fatal stroke)-was centrally assessed by the GCS follow-up team, who were masked to allocation status. We did intention-to-treat analyses by including all participants who met eligibility criteria in the two study groups. The trial was registered with ClinicalTrials.gov, number NCT01271985. Findings Between Feb 22, 2011, and April 15, 2013, we enrolled 6838 individuals into the study-3417 (in 116 clusters) in the minimal care group and 3421 (in 120 clusters) in the polypill group. 1761 (51.5) of 3421 participants in the polypill group were women, as were 1679 (49.1) of 3417 participants in the minimal care group. Median adherence to polypill tablets was 80.5 (IQR 48.5-92.2). During follow-up, 301 (8.8) of 3417 participants in the minimal care group had major cardiovascular events compared with 202 (5.9) of 3421 participants in the polypill group (adjusted hazard ratio HR 0.66, 95% CI 0.55-0.80). We found no statistically significant interaction with the presence (HR 0.61, 95% CI 0.49-0.75) or absence of pre-existing cardiovascular disease (0.80; 0.51-1.12; p(interaction) = 0.19). When restricted to participants in the polypill group with high adherence, the reduction in the risk of major cardiovascular events was even greater compared with the minimal care group (adjusted HR 0.43, 95% CI 0.33-0.55). The frequency of adverse events was similar between the two study groups. 21 intracranial haemorrhages were reported during the 5 years of follow-up-ten participants in the polypill group and 11 participants in the minimal care group. There were 13 physicianconfirmed diagnoses of upper gastrointestinal bleeding in the polypill group and nine in the minimal care group. Interpretation Use of polypill was effective in preventing major cardiovascular events. Medication adherence was high and adverse event numbers were low. The polypill strategy could be considered as an additional effective component in controlling cardiovascular diseases, especially in LMICs.